# Math Help - Circle Geometry - Direct Proofs

1. ## Circle Geometry - Direct Proofs

Hi I need help on these 2 questions, I have no clue what to do.

2. 1) Let O be the center of the circle. Then the triangle ODA and ODC are congruent (because OD=OD, OA=OC and angles ODA and ODC are right). Therefore AD=DC.
Then the height BD is also median and that happens in an isosceles triangle.

3. 2)
AC also bisects the arc BD. Then $\widehat{BEC}=\widehat{CED}$ But $\widehat{BEC}+\widehat{CED}=180\Rightarrow \widehat{BEC}=\widehat{CED}=90$